Shoe for track chain assembly

ABSTRACT

This disclosure relates to a track chain assembly which includes an endless chain supporting a plurality of track shoes and entrained over spaced sprockets. The track shoes have overlapping portions when the shoes are located between sprockets and are angularly related to each other while the shoes are passing over the sprockets. One end of each of the track shoes has a pair of lugs extending beyond one end portion for engaging an adjacent shoe while the shoes are passing over the sprockets so as to prevent pivotal movement of the shoes transversely of the longitudinal axis of the endless chain and transmit any load applied to one of the shoes from that shoe to adjacent shoes. In one embodiment of the disclosure, each shoe also has recesses extending from the lower surface and upwardly tapered surfaces beyond the recesses adjacent the respective lateral edges.

United States Patent 1191 Symmank Oct. 9, 1973 SHOE FOR TRACK CHAIN ASSEMBLY William D. Symmank, Schofield, Wis.

[73] Assignee: J. I. Case Company, Racine, Wis. [22] Filed: June 1, 1972 [21] Appl. No.: 258,855

[75] Inventor:

1,339,786 11/1920 Porter 305/47 Primary Examiner-Richard J. Johnson Attorney--Max Dressler et al.

[5 7] ABSTRACT This disclosure relates to a track chain assembly which includes an endless chain supporting a plurality of track shoes and entrained over spaced sprockets. The track shoes have overlapping portions when the shoes are located between sprockets and are angularly re,- lated to each other while the shoes are passing over the sprockets. One end of each of the track shoes has a pair of lugs extending beyond one end portion for engaging an adjacent shoe while the shoes are passing over the sprockets so as to prevent pivotal movement of the shoes transversely of the longitudinal axis of the endless chain and transmit any load applied to one of the shoes from that shoe to adjacent shoes.

In one embodiment of the disclosure, each shoe also has recesses extending from the lower surface and upwardly tapered surfaces beyond the recesses adjacent the respective lateral edges.

6 Claims, 11 Drawing Figures SHOE FOR TRACK CHAIN ASSEMBLY BACKGROUND OF TI'IE INVENTION The present invention relates generally to endless track chain assemblies, and more particularly to an improved track shoeforming part of an endless chain assembly. I

As is well known to those skilled in the art, crawler type vehicles are supported on endless chain assemblies. There are generally two types of track chain assemblies which are commonly utilized for crawler vehicles, such as tractors. One of these types is anendless chain which is supported on a drive sprocket'and an idler sprocket with a plurality of shoes attached to the chain for supporting and driving the vehicle. The track shoes are normally attached to the links of the endless chain through the use of bolts and the shoes have overlapping portions which come in contact with each other as the track shoes come in contact with the supporting terrain so that the load is partially supported by a plurality of track shoes.

In certain instances it is necessary to have extremely wide track shoes in order to have sufficient surface area and traction for a particular-vehicle in certain types of terrain. In operating in rather rough terrain, difficulties have been encountered with track shoes of the relatively wide type.

Thus, in the useofa wide track shoe in rough terrain, it is possible for the track shoes to engage the terrain before the shoe passes from the sprocket to the lower flight portion of the chain. In so doing, the forces applied to a shoe, particular adjacent one outer edge, will cause a pivotal movement of the shoe about the longitudinal axis of the endless chain. This pivotal movement may occur at times when the adjacent pairs of track shoes are at an angular relation relative to each other, i.e., as they must be when traveling over the drive or idler sprockets, where the adjacent overlapping end portions of the adjacent pairs of track shoes will be spaced from each other. This will allow the end of the one track shoe to .be pivoted into the ultimate path of movement of the end of the adjacent track shoe placing these ends in alignment with each other.lf the force remains on one track shoe as the two adjacent shoes are moved from the radial portion of the endless chain assembly to the straight line flight portion, a wedging affect will occur and will produce tremendous stress on the bolts supporting the shoes on the endless chain. In fact, in many instances, the shear'forces applied to the bolts will cause a rupture of the bolt. In addition, such wedging condition between adjacent pairs of track shoes causes undesirable forces and loads to be applied to the entire endless chain assembly.

SUMMARY OF THE INVENTION The present invention alleviates the above problem by insuring that the track shoes cannot be deflected or pivoted relative to the longitudinal axis of the endless chain while the adjacent ends of the chains track shoes are in spaced relationship to each other, as they are when passing over the idler and/or drive sprockets. Stated another way, the present invention contemplates track shoes in which any load imparted to one of the shoes is automatically transmitted to the next adjacent shoe even when the respective shoes are at an angularly' related position relative to each other and have adjacent ends spaced from each other.

The present invention contemplates an endless track chain assembly whichincludes an endless chain having pivotally interconnected links and supporting a plurality of shoes each having overlapping portions. The overlapping portions of the shoes are defined by an offset on one end of each shoe which produces a recess having a surface for receiving an end portion of the opposite ends of the respective shoes when the shoes are located in an aligned condition and are moving between spaced sprockets supporting the endless chain. The opposite ends of each of the track shoes include means in the form of spaced lugs for engaging an adjacent-shoe to 1 prevent pivotal movement of the shoes transversely of the longitudinal axis of chain as the shoes pass over the sprockets and (2) transmit loads applied to one of the shoes to an adjacent shoe when the end portions of the respective shoes are spaced from each other, as occurs when they pass over the sprockets.

In one embodiment of the invention, each track shoe has also at least one recess extending above the lower surface of theshoe on an intermediate portion of the 'shoe. In addition, th lower surface of each shoe has upwardly inclined flat portions adjacent the lateral edges. The upwardly inclined flat portions of the lower surface of each shoe produce a-lifting effect during the turning of the vehicle supported by the endless chains to reduce the interruption of the supporting terrain to a minimum while the recesses fill with mud and/or dirt to increase the driving force for the vehicle. The increased driving force results from the increased coefficient of friction between .the mud and/or dirt in the recess and mud and/or dirt defining the supporting terram.

BRIEF DESCRIPTION OF SEVERAL vIEws OF DRAWINGS FIG. 1 is a perspective view of several shoes as they would be arranged on an endless chain;

FIG. 2 is a vertical sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a schematic illustration of the endless chain supported on a pair of spaced sprockets;

FIG. 4 is a fragmentary side elevation of two adjacent shoes; I

FIG. 5 is a bottom perspective view of a modified form of track shoe;

FIG. 6 is a top perspective view of the track shoe shown in FIG. 5;

FIG. 7 is a top plan view of the track shoe shown in FIG. 5;

FIG. 8 is a bottom plan view of the track shoe shown in FIG. 5;

I 10- 10 of FIG. 9 showing two adjacent shoes in the po- DETAILED DESCRIPTION While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail several specific embodiments, with the understanding that the present 3 disclosure is to be considered as an exempliflcation of the principles of the invention and is not intended to limit the invention to the embodiments illustrated.

FIG. 3 of the drawings schematically illustrates endless chain assembly supported on drive sprocket l2 and idler or driven sprocket 14 as is conventional in track-type vehicles such as crawler tractors. As was indicated above, one type of endless track chain assembly includes chain 16 consisting of a plurality of links l8 pivotally interconnected at 20 and supported on the respective sprockets 12 and 14. Sprockets 12 and 14 are supported on longitudinally spaced pivot axes so as to define upper and lower straight flight portions 22 and 24 and radial end portions 26. The endless chain supports a plurality of track shoes generally designated by the reference numeral 30, connected to links 18 by bolts 32 (FIG. 2). Since the endless chain and sprockets as well as the remainder of the veh icle only form a basis of environment for the present invention, the chain assembly and sprockets have been schematically illustrated.

In the normal operation of the endless chain assembly, shoes are arranged in substantially end-to-end relationship as the supporting chain is moved along straight flight portions 22 and 24 and are angularly related relative to each other as the supporting links pass over the circumference of circular sprockets l2 and 14. In the normal construction of track shoes of this type, the shoes are provided with some means for transmitting some of the load received on one of the shoes to the next adjacent shoes as the endless track assembly passes along lower flight 24 during which it supports and moves the vehicle along the terrain.

As was indicated above, in some instances it is necessary to use relatively large rectangular shoe assemblies in cases where relatively large vehicles are used in substantially soft terrain. In using the shoeshaving a substantial length and even greater width, it has been found that a large number of bolts 32 are destructed when the vehicle is used in rather rough terrain. This is particularly true when the width of the track shoe is on the order of three times the length, the length being considered the dimension of the shoe in the direction of travel of the vehicle.

After considerable study of the problem, it has been determined that the primary reason for shearing of the bolts results from a load being applied to shoe 30 while the shoe is passing over one of the sprockets.

An inspection of the endless chain assemblies shows that the adjacent ends of two shoes of relatively large size will have a small gap, generally designated at 40, when at least one of the adjacent shoes is on the radial portion of the track. Thus, a force being applied to shoe 30a in FIG. 1 along one edge of the shoe, designated by the arrow F, results in deflection or pivoting of shoe 300 relative to the longitudinal axis of the chain assembly. In very wide shoes only a small degree of pivoting will move the lateral edges of adjacent shoes sufficiently to align the adjacent ends of shoes 30a and 30b and produce a wedging action when the shoes are moved to the straight portion of the flight causing serious loading of the retaining bolts 32 as well as theremainder of the entire chain assembly. In some instances, the result is that retaining bolts 32 supporting track shoes 30 upon links 18 of the chain will be sheared and must be replaced.

However, according to the present invention, the pivotal movement or flexing of adjacent shoes about the longitudinal axis of the chain, while they are along the radial portions of the track and there is a small gap between adjacent ends of the shoes, is eliminated and any loads applied to one shoe while it is on the radial portion of the track will be transmitted to a next adjacent shoe.

As more clearly shown in FIG. 1, the means for preventing the shoes from being deflected while they are located along the radial portions of the flight, is in the form of a pair of spaced lugs 50, which are fixedly secured to the shoes adjacent one end thereof and extend beyond the end portion of the shoe a sufficient distance to overlie a portion of the next adjacent shoe while the respective shoes are traveling over the radial portions of the track.

In the illustrated embodiment of the present invention, respective shoes 30a, 30b, and 30c all have overlapping end portions 52 when the shoes are in end-toend aligned relationship along the straight flight portions 22 and 24. These overlaping end portions are defined by an offset portion or lip 54 adjacent one end of each track shoe with the lip or offset portion defining a recess 56 having a generally arcuate upper surface 58.

When a load is applied adjacent one edge or end of shoe 3011 while the shoe and next adjacent shoe are moving along lower flight 24, shoe 30b will deflect somewhat causing surface 54 to engage lower arcuate surface 62 of end portion 60 of track shoe 30a resulting in track shoe 30c supporting part of the load applied to track shoe 30b. Should a load be applied to a track shoe while the shoes is still located along the radial portion of the flight, such as shown by the force indicated at F along one edge of track shoe 30a, substantial deflection or movement from the normal position of track shoe 30a will be prevented by engagement of lug means 50 on shoe 30b with the end portion of shoe 30a.

This is accomplished by'having lugs 50 extend across gap 40 created between the outer end of offset lip 54 and end portion 60 of two adjacent shoes with lower surfaces 72 of lugs 50 engaging the upper surface of the next adjacent shoe. This relation of lugs 50 is shown in FIG. 4 with respect to shoes 30a and 30b.

As shown in FIG. 1, the respective lugs 50 are two in number and are located in close proximity to opposite sides of lateral edges and 71 on each of the track shoes. In addition, contacting surfaces 72 of lugs 50 are in the form of lower arcuate surfaces that have a configuration corresponding to the cross-sectional configuration of arcuate surface 58 that is defined on offset lip 54 on one end of each shoe. The transverse dimension of the lower arcuate surfaces 72 on lugs 50 is many times less than the transverse dimension of the shoe.

As explained above, adjacent arcuate surfaces 58 and 62 a're normally spaced from each other by a small dimension, on the order of one-eighth inch, when no external forces are being applied to either of the adjacent shoes. However, when the respective shoes are moving along lower flight 24, the respective shoes support the entire weight of the vehicle on the terrain. During this time, the the'adjacent shoes are deflective sufficiently to produce engagement between arcuate surfaces 58 and 62. Thus, the load supported by one shoe is transmitted to the next adjacent shoe so that the entire load of the vehicle is more evenly distributed over several shoes.

arcuate surface 58 when no external force is being applied to the shoes and adjacent shoes are moving along the radial path defined by the periphery of the sprockets.

duces wear of the various parts during normal operation, thereby extending the service life of the unit substantially. Extended surface engagement between arcuate surfaces 58 and 62 occurs only when the shoes are along lower flight 24 and a load is being supported by the shoes. At this time there is virtually no relative movement between the adjacent shoes,'which greatly reduces the frictional wear and increases the service life of the respective shoes.

Since arcuate surfaces 58 and 62 are not in engagement with each other while the shoes are traveling along the radiaLportion of the chain path, and only the limited surface area of the lower arcuate surface of one of the lugs is ever in engagement with next adjacent shoe, frictional wear resulting from possible contact between adjacent shoes when an external force is applied to the shoes while traveling on the radial portion of the track is substantially eliminated.

A slightly modified form of track shoe having the present invention incorporated therein is shown in FIGS. 5 through 11. Shoe 100 is shown as having a width between opposite lateral edges 102 which is substantially greater and on the order of. three times the length between opposite ends 104. Shoe 100 has a plurality of elongated recesses or pockets 106 extending from lower surface 108 towards upper surface 109 (FIG. 9). Each pocket is substantially rectangular in cross-section as shown in FIG. 7 and has openings 110 for receiving bolts that secure the shoe to the track chain.

Pockets 106 are adapted to receive dirt or mud from the supporting terrain during the operation of the vehicle and the'exposed surface of the dirt adjacent lower surface 1080f track shoe 100 substantially increases the coefficient of friction between the shoe and the supporting terrain thereby increasing the traction of the chain asembly for the vehicle.

Shoe 100 also incorporates means on the outer edge thereof that substantially reduces the interruption of the supporting terrain during turning movements of the vehicle. It is well known that in ordinary track chainshoe assemblies for track vehicles, the outer edges of the shoes tend to cut the supporting terrain during turning movement of the vehicle to develop the desired lateral forces required to produce the turning action for the vehicle. To alleviate this problem, track shoe 100 has means adjacent opposite lateral edges 102 to produce a lifting effect for the vehicle when the vehicle is directed away from its straight line path longitudinally of the track chain assembly. As is most clearly shown in FIG. 9, lower surface 108 of track-shoel00 has first andsecond upwardly and outwardly directed flat tapered portions 114 that terminate adjacent opposite The arrangement described above substantially relateral edges 102 of track shoe 100. The upperwardly and outwardly tapered surfaces will produce a lifting action for the outer edge of each shoe when the vehicle is being turned in either direction away from the longitudinal axis for the chain assembly.

As in the previous embodiment, track shoe 100 includes offset portion 116 (FIG. on one end 104 with offset portion or lip 116 having upper arcuate surface 118. Likewise,'opposite end 104 of each track shoe has a corresponding lower arcuate surface 120 which overlaps arcuate surface 1 18 on the next adjacent shoe and is adapted to engage the upper arcuate surface of the adjacent shoe when the shoes are located between the sprockets on lower flight 24 and a forceis applied to lower surface 108 of the next adjacent shoe. This relationship is most clearly shown in FIG. 10.

Each track shoe 100 again includes first and second lugs that are located adjacent opposed lateral edges 102 and are formed integral with the main body defining lower surface 108 and corresponding upper surface 109. Each lug 130 has lower arcuate surface 132 that defines an extension of arcuate surface 120 on one end of the track shoe.

Track shoes 100 are attached to endless chain 16 in a similar fashion to that described in connection with the embodiment of FIGS. 1 through 4 and the adjacent shoes will be located in end-to-end relation as shown in FIG. 10 when the shoes are traveling along lower flight 24. When the shoes are located along radial portions 26 of the chain flight, the adjacent shoes will assume a position generally indicated in FIG. 11 wherein adjacent ends 104 of adjacent shoes are spaced from each other to produce a small gap with the lugs 130 extending across the gap and have lower surface 132 above upper surface 1 18.

As in the previous embodiment, the transverse dimension of the arcuate surfaces on lugs 130 is many times less than the'total transverse dimension of the track shoe. For example, assuming a'track shoe having a length of approximately 8 inches between opposite ends 104 and width of 24 inches between lateral edges 102, each lug would have a transverse dimension of ap-. proximately 2 inches. i It should be noted that track shoe 100 is shown as having a pair of openings extending through the body of the shoe between the outer surface 114 and recess 106. These openings may be utilized for attachment of a logger lug, if desired.

As will be appreciated from the above description the present invention provides a simple and inexpensive expedient for considerably increasing the service life of a chain assembly and particularly the service of the retaining bolts for supporting the track shoes on the endless chain. The use of two small lugs adjacent the oppo site lateral -edges of the track shoe provides a sufficient surface area for engagement with the next adjacent shoe to prevent the shoes from being pivoted about the track chain assembly. Thus, a partial load may readily be supported by the shoes as they are passing over the radial sprockets and there is no possibility of having the two adjacent shoes moved into a position where opposite ends of the shoes can produce a wedging action that will shear the bolts.

I claim:

1. A track chain assembly of the type having a plurality of links pivotally interconnected to form an endless chain supported on spaced sprockets; a plurality of track shoes supported on said links, each of said track shoes having a width between opposite lateral edges that is substantially greater than the length between opposite ends, each shoe having an offset portion on one end extending between said lateral edges, said offset portion having an upper arcuate surface, each shoe having a corresponding lower arcuate surface on its opposite end overlapping said upper arcuate surface and adapted to engage the upper arcuate surface of a next adjacent shoe when the shoes are located between said sprockets and a force is applied to the lower surface of the next adjacent shoe, said arcuate surfaces being spaced from each other in a direction longitudinally of said chain when the shoes are located on said sprockets to produce a gap between the opposite end of one shoe and the offset portion of the next adjacent shoe; and a pair of lugs respectively adjacent the lateral edges of each shoe on its opposite end, each lug extending across said gap and having a lower surface adapted to engage the next adjacent shoe when a force is produced on the lower surface of the next adjacent shoe, said lugs preventing pivotal movement of adjacent shoes about the longitudinal axis of said chain when said shoes are passing over said sprockets.

2. A track chain assembly as defined in claim 1, in which said lugs each have a lower arcuate surface that defines an extension of said lower arcuate surface on the end of said shoe.

3. A track chain assembly as defined in claim 1, in which each shoe has a width approximately three times its length.

4. A track chain assembly as defined in claim 3, in which each lug has a width many times less than the width of the shoe to produce only limited area adapted to engage the next adjacent shoe.

5. A track shoe as defined in claim 1, in which each shoe has a pocket extending from its lower surface to receive material from the supporting terrain thereby increasing the traction of said shoes.

6. A track shoe as defined in claim 5, in which the lower surface of each shoe has upwardly and outwardly inclined flat edge portions adjacent said lateral edges.

l t i 

1. A track chain assembly of the type having a plurality of links pivotally interconnected to form an endless chain supported on spaced sprockets; a plurality of track shoes supported on said links, each of said track shoes having a width between opposite lateral edges that is substantially greater than the length between opposite ends, each shoe having an offset portion on one end extending between said lateral edges, said offset portion having an upper arcuate surface, each shoe having a corresponding lower arcuate surface on its opposite end overlapping said upper arcuate surface and adapted to engage the upper arcuate surface of a next adjacent shoe when the shoes are located between said sprockets and a force is applied to the lower surface of the next adjacent shoe, said arcuate surfaces being spaced from each other in a direction longitudinally of said chain when the shoes are located on said sprockets to produce a gap between the opposite end of one shoe and the offset portion of the next adjacent shoe; and a pair of lugs respectively adjacent the lateral edges of each shoe on its opposite end, each lug extending across said gap and having a lower surface adapted to engage the next adjacent shoe when a force is produced on the lower surface of the next adjacent shoe, said lugs preventing pivotal movement of adjacent shoes about the longitudinal axis of said chain when said shoes are passing over said sprockets.
 2. A track chain assembly as defined in claim 1, in which said lugs each have a lower arcuate surface that defines an extension of said lower arcuate surface on the end of said shoe.
 3. A track chain assembly as defined in claim 1, in which each shoe has a width approximately three times its length.
 4. A track chain assembly as defined in claim 3, in which each lug has a width many times less than the width of the shoe to produce only limited area adapted to engage the next adjacent shoe.
 5. A track shoe as defined in claim 1, in which each shoe has a pocket extending from its lower surface to receive material from the supporting terrain thereby increasing the traction of said shoes.
 6. A track shoe as defined in claim 5, in which the lower surface of each shoe has upwardly and outwardly inclined flat edge portions adjacent said lateral edges. 